Meeting Abstract
In 1990, a hypothesis was put forth that squids obtain a fairly large portion (as much as 50+%) of their oxygen via simple diffusion across the skin rather than across the gills. This was proposed initially to explain the paradox of how squids sustain oxygen delivery to their tissues despite an extremely high Haldane coefficient. Although this idea has good theoretical support and has been generally regarded as valid for the two decades since, no empirical examinations have been conducted to assess the validity of this hypothesis. In this study, we examined this claim via manipulative experiments on two squid species, Doryteuthis pealeii and Lolliguncula brevis, by mechanically separating the oxygen consumption through the gill and skin of an intact animal using respirometry in a divided chamber. We found that this hypothesis, although enjoying good circumstantial evidence, was not supported by empirical examination. In contrast, we estimate that squids at rest obtain no more than 10% of their O2 cutaneously, with the majority of O2 entering via the traditional branchial pathway. We furthermore re-examine the theoretical evidence that has supported the cutaneous respiration hypothesis and discuss its implications in a non-cutaneous context.
